I have a 2000 Chrysler 300M. Recently I got in the car and shut the door normally, not a hard slam or anything, and the driver side window just shattered to pieces. After having the glass replaced I had my mechanic check out the window regulator thinking that may have have been loose or in some way caused the glass to break. It checked out fine, no problem with the mechanism could be found. I’ve been using the window since then for about 3 months with no problems. What could have caused this window to crumble?

Glass is a funny thing. It’s very strong, but the tiniest little flaw can allow it to break unexpectedly. Some vehicle windows break while the vehicle is just sitting. There may have been a small chip or crack you didn’t know about.

If there were no problems with the mechanism I wouldn’t worry about it. Drive on.

A car this age probably encountered some new nick, ding, or scratch along the way but there’s no saying just how long it lasted till the break.

A major scratch would be equivilant to the way they cut glass normaly, They merely score the surface and flex the glass.

An edge nick would be a fatal injury lasting months to years until just the wrong combination of circumstances occurs. Too much flex, too much temp change etc.

Having the window down just a tad ( common in summer ) will allow that extra flex.

When receiving a delivery of glass we inspect, not only visually, but with our finger tips along the edges before we accept it as o.k.
Just a nick, like on the edge of your living room end table, will be fatal in the long run.

I was interested and googled a Life Hammer. I wonder if a small rock or pebble could have wedged in the mechanism, or perhaps a metal piece inside came into contact with the glass; then shattered the window when the door was closed. Trying to track down the actual cause, I agree, could drive you crazy.

In addition to the comments about a minor chip, automotive side window glass is “tempered”. This is a heat treating process that creates a stronger glass, but also creates a pre-stressed structure such that if any part of the glass fractures the entire pane shatters into tiny pieces. One tiny chip or stress-induced failure manifests itself as a shattered panel. This is required in car side windows for safety purposes.